By putting patients literally into a state of suspended animation—or "emergency preservation," as Tisherman calls it—the surgeons intend to preserve brain functioning long enough to close wounds that would otherwise be fatal.

The University of Pittsburgh hospital study will treat ten patients with this supercooling protocol and compare their survival rates with those of ten patients given standard CPR and surgery without cooling. If the protocol works on the first group, investigators will refine the procedure as necessary and try it again with another ten patients.

As part of the study, any gunshot or stabbing victim who comes to the hospital ER in cardiac arrest will first get standard treatment: open-chest manual manipulation to restart the heart. (Closed-chest CPR doesn't work in someone who has lost massive amounts of blood.) If manual manipulation fails, the study team will go into "preservation" mode. They will thread a large catheter directly into the patient's aorta, the main artery of the heart, and infuse a cold saline solution that Tisherman calls a "flush." The solution is 50 degrees Fahrenheit, about the same as very cold tap water. As it circulates, it will chill first the heart and brain and then the rest of the body, until the patient's body temperature is also 50 degrees. The cooldown will take 15 to 20 minutes, at which point the patient will have no blood, no breath, no movement or any other outward sign of life.

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Doctors use a catheter to push cold fluids into the aorta of patients who have lost large amounts of blood.

PHOTOGRAPH BY UPMC

Tisherman hopes that rendering the victim not quite dead will "buy time for the surgeons to get control of the bleeding." He estimates that the chilled state will allow about one hour to do "damage control"—stopping the bleeding and repairing the major injuries. The surgeons will then reinfuse the body with blood, restart the heart, and let the patient slowly return to a normal body temperature over the course of the next two hours. Later they will have time to go back to repair any secondary wounds. If the experiment works, the patient will return to full functioning, none the worse for wear for having been, for about an hour, clinically dead.

The original impulse for this approach dates back to the Vietnam War. Military surgeons at the time noted that the leading cause of combat death was rapid blood loss in the first 5 to 20 minutes after injury—even though about one-third of the soldiers had wounds that wouldn't have been fatal in a typical emergency room. If the current study, funded by the Department of Defense, is successful, medics may someday bring the supercooling technique to the battlefield using portable equipment. This would give wounded soldiers time to get to a hospital before they bleed to death.

There could be ethical concerns about conducting research on patients who are not conscious, are in cardiac arrest, and are therefore in no position to give informed consent. But the Food and Drug Administration, which must eventually approve the procedure and the devices used—several of which are patented by Tisherman and Kochanek—allows for exemption from informed consent in the case of life-threatening emergencies. The Pitt investigators also provided a layer of implied consent by conducting a series of town hall meetings in the surrounding community to describe the study and give people the option of wearing a bracelet declaring their wish to opt out of participation in the project. While it's not a perfect system, Elizabeth Chaitin, a professor of palliative care and medical ethics at the University of Pittsburgh, notes that the effort is important in establishing community trust in the scientists. And after three years of outreach efforts, no one has yet asked for a bracelet.

"No one wakes up in the morning expecting to be shot in gang warfare that night," says Chaitlin.

Watch the process in action:

An earlier version of this story incorrectly referred to the cold saline solution that Tisherman uses as a "slush." It is called a "flush."